JP3373669B2 - Thermal recording material and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material and a method for producing the same, and more particularly to a heat-sensitive recording material having a high image quality and a uniform surface and a method for producing the same.

[0002]

2. Description of the Related Art Thermosensitive recording materials are inexpensive, have high reliability in spite of the simple recording apparatus used, and require no maintenance. Used in the field. With the increasing demand for heat-sensitive recording materials, it is desired to manufacture higher-quality heat-sensitive recording materials with higher production efficiency. From this point of view, attempts have been made so far to incorporate various surfactants and thickeners in the thermosensitive recording layer, but the thermosensitive recording layer has a uniform surface and can record high-quality images. It was still insufficient in terms of obtaining a recording material.

[0003]

The inventors of the present invention have made diligent studies to solve the above-mentioned drawbacks, and have found that the coating limit speed jumps when a certain amount of a certain compound is added to the coating solution. The present invention has been achieved by finding out that it is improved.

Therefore, it is a first object of the present invention to provide a heat-sensitive recording material having a uniform surface shape and capable of recording a high quality image. The second object of the present invention is to
An object of the present invention is to provide a method for efficiently producing a high quality thermal recording material.

[0005]

The above objects of the present invention are to provide a heat-sensitive recording layer comprising, on a support, a heat-sensitive recording layer containing at least a color-developing agent and a color-developing agent which develops color by contacting with the color-developing agent. a recording material, the thermosensitive recording layer, was achieved by a compound represented by the following formula 2 in the heat-sensitive recording material and a manufacturing method thereof, characterized that it contained 0.001% by weight.

[Chemical 2] In the formula, m represents an integer of 3 to 20, n represents an integer of 7 to 47, and the ratio of m and n is between 1: 9 and 5: 5, preferably between 2: 8 and 4: 6. Is.

In the heat-sensitive recording material of the present invention, an image is recorded by causing a color-developing agent and a color-developing agent, which are separated from each other at room temperature, to come into contact with each other by heating to develop a color. The combination of the color-developing agent and the color-developing agent used in the present invention is not particularly limited, and any substance can be used as long as it causes a color-forming reaction based on contact of the substance by heating. Specifically, a combination of an electron-donating dye precursor (color former) and an electron-accepting compound (developing agent) or a combination of a diazo compound (color former) and a coupling compound (developing agent) is used. Is preferred. Especially when the former combination is adopted, the stability of the printed image can be greatly improved.

The electron-donating dye precursor used in the present invention is not particularly limited, but it has a property of developing a color by donating an electron or accepting a proton such as an acid, and a lactone. Compounds having a partial skeleton such as lactam, sultone, spiropyran, ester, amide, etc., which are ring-opened or cleaved upon contact with a color developer, are generally colorless compounds.

As a concrete example, Japanese Patent Laid-Open No. 55-2272.
Those described in Japanese Patent No. 53, etc. can be mentioned. As an example of some of these, as a triarylmethane-based compound, 3,3-bis (p-dimethylaminophenyl)-
6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,3dimethylindole-3
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide and the like;

As the diphenylmethane compound, 4,
4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine, N-
2,4,5-trichlorophenyl leuco auramine and the like;

As a xanthene compound, rhodamine-
B-anilinolactam, rhodamine- (p-nitrino)
Lactam, 2- (dibenzylamino) fluorane, 2-
Anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-dibutylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-isoamylaminofluorane, 2- Anilino-3
-Methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-N
-Ethyl-N-isobutylaminofluorane, 2-anilino-6-dibutylaminofluorane, 2-anilino-
3-Methyl-6-N-methyl-N-tetrahydrofurfurylaminofluorane, 2-anilino-3-methyl-6
-Piperidinoaminofluorane, 2- (o-chloroanilino) -6-diethylaminofluorane, 2- (3,4
-Dichloroanilino) -6-diethylaminofluorane and the like;

Benzoyl leuco methylene blue, p-nitrobenzyl leuco methylene blue and the like as thiazine compounds; 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran 3,3'-dichloro-spiro-dinaphthopyran as spiro compounds. , 3-
Benzylspiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzopyran and the like.

As the electron-accepting compound (developing agent) for these color-developing agents, phenolic compounds, organic acids or metal salts thereof, and acidic substances such as oxybenzoic acid esters are used. Particularly, phenolic compounds or salicylic acid are used. Derivatives and polyvalent metal salts thereof are preferred.

Examples of the phenolic compound include 2,
2'-bis (4-hydroxyphenyl) propane, 4-
t-butylphenol, 4-phenylphenol, 4-
Hydroxydiphenoxide, 1,1′-bis (3-chloro-4-hydroxyphenyl) cyclohexane, 1,
1'-bis (3-chloro-4-hydroxyphenyl)-
2-ethylbutane, 4,4'-sec-isooctylidene diphenol, 4,4'-sec-butylidene diphenol, 4-tert-octylphenol, 4-p-
There are methylphenylphenol, 4,4'-methylcyclohexylidenephenol, 4,4'-isopentylidenephenol, benzyl p-hydroxybenzoate and the like.

Examples of salicylic acid derivatives and polyvalent metal salts thereof include 4-pentadecylsalicylic acid and 3,5-
Di (α-methylbenzyl) salicylic acid, 3,5-di (t
er-octyl) salicylic acid, 5-octadecylsalicylic acid, 5-α- (p-α-methylbenzylphenyl) ethylsalicylic acid, 3-α-methylbenzyl-5-ter
-Octylsalicylic acid, 5-tetradecylsalicylic acid,
4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid and the like, and zinc, aluminum, calcium, copper and lead of these. There is salt etc.

In particular, when a phenolic compound is used, the effect of suppressing background fog is remarkable. Examples of the heat-sensitive recording material in which such an electron-donating dye precursor (color former) and an electron-accepting compound (developing agent) are combined include:
U.S. Pat. Nos. 4,771,034 and 4,839,332
No. 6, JP-A-63-22682, 63-2656.
82, 63-227375 and JP-A-1
It is described in detail in Japanese Patent Laid-Open No. 105782.

The diazo compound that can be used in the present invention is a compound that reacts with a developer called a coupling component described below to develop a desired hue, and emits light of a specific wavelength before the reaction. It is a photodecomposable diazo compound that decomposes when received and no longer has the ability to develop color even when the coupling component acts.

The hue in this coloring system is mainly determined by the diazo dye produced by the reaction of the diazo compound and the coupling component. Therefore, as is well known,
By changing the chemical structure of the diazo compound or the chemical structure of the coupling component, the coloring hue can be easily changed, and almost any coloring hue can be obtained depending on the combination.

The photodecomposable diazo compound in the present invention mainly means an aromatic diazo compound, and more specifically, an aromatic diazonium salt, a diazosulfonate compound, a diazoamino compound and the like. Details of these diazo compounds are described in, for example, JP-A-2-136286.

The coupling component for forming a dye by coupling with the diazo compound (diazonium salt) used in the present invention includes, for example, 2-hydroxy-3-naphthoic acid anilide and resorcin as a starting point. -14
The thing described in the 6678 gazette can be mentioned. Further, an image having an arbitrary color tone can be obtained by using two or more of these coupling components in combination.

Since the coupling reaction between these diazo compounds and the coupling component easily occurs in a basic atmosphere, it is preferable to add a basic substance in the layer. Specific examples of these basic substances are described in, for example, JP-A-61-29.
It is described in Japanese Patent No. 1183. Two or more basic substances may be used in combination. A heat-sensitive recording material using a combination of the above-mentioned diazo compound (color former) and coupling compound (developer) is disclosed in, for example, JP-B-2-28479.
No. 2, 31-674, and No. 2-20434.

The color former or developer used in the present invention can be usually used as a solid dispersion, but from the viewpoint of raw storability of the thermosensitive recording layer, such as preventing contact between the color former and the developer at room temperature. From the viewpoints of (fog prevention) and the control of color development sensitivity of color development with desired thermal energy, in the present invention, either a color former or a developer is used, especially a color former is encapsulated in microcapsules. It is preferable.

Any of an interfacial polymerization method, an internal polymerization method, and an external polymerization method can be adopted for producing the microcapsules which can be used in the present invention. In particular, a core containing a color former is used. It is preferable to employ an interfacial polymerization method in which a substance is emulsified in an aqueous solution in which a water-soluble polymer is dissolved and then a wall of the polymer substance is formed around the oil droplets.

The reactant forming the polymer substance is added inside the oil droplet and / or outside the oil droplet. Specific examples of the polymer substance include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer and the like. Preferred polymeric substances are polyurethanes, polyureas, polyamides, polyesters and polycarbonates, particularly preferably polyurethanes and polyureas. Two or more polymer substances can be used in combination.

Specific examples of the water-soluble polymer include gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like. Details of the method for producing the microcapsule composite wall are described in, for example, Japanese Patent Application Laid-Open No. 58-66948.

In order to microencapsulate the color former, it is preferable to use it by dissolving it in an organic solvent. Examples of such an organic solvent include ethyl acetate, methyl acetate, carbon tetrachloride, chloroform, methanol, ethanol, n-butanol, low-boiling solvents such as dioxane, acetone and benzene, and carboxylic acid esters such as phosphoric acid ester and phthalic acid ester. , Fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylnaphthalenes, diarylethanes and the like. Such an organic solvent is described in detail in JP-A-4-19778.

In the case of microcapsules containing a color-forming agent, a solid sensitizer for swelling the microcapsule wall when heated can be further added. As the solid sensitizer, those which are solid at room temperature and have a melting point of 50 ° C. or higher, preferably 120 ° C. or lower can be selected and used from among the plasticizers of polymers used for the microcapsule wall. For example, when the wall material is made of polyurea or polyurethane, a hydroxy compound, a carbamic acid ester compound, an aromatic alkoxy compound, an organic sulfonamide compound, an aliphatic amide compound, an arylamide compound and the like are preferably used.

In the present invention, when a diazo compound is used as a color former, a color former may be used. The coloring aid that can be used in the present invention is a substance that increases the coloring density during heating printing or lowers the minimum coloring temperature, lowers the melting point of the coupling component or the diazo compound, or capsule wall. This is to create a situation in which the diazo compound and the coupling component easily react with each other by the action of lowering the softening point of.

In the present invention, when the color developer is not microencapsulated, the transparency of the heat-sensitive recording layer is improved to improve the light transmittance of the heat-sensitive recording material to obtain a heat-sensitive recording material used for OHP. Or, from the viewpoint of laminating multiple heat-sensitive layers to form a multicolor heat-sensitive recording material, after dissolving it in an organic solvent that is sparingly soluble or insoluble in water, it contains a surfactant and protects the water-soluble polymer. It can also be used in the form of a dispersion obtained by mixing and emulsifying with an aqueous phase having a colloid.

The organic solvent used in this case can be appropriately selected from high boiling point oils. Among them, preferable oils include dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl, diisobutylbiphenyl, 1-methyl-1-dimethylphenyl-1-phenylmethane, and 1 in addition to esters.
-Ethyl-1-dimethylphenyl-1-phenylmethane, 1-propyl-1-dimethylphenyl-1-phenylmethane, triallylmethane (eg tritoluylmethane, toluyldiphenylmethane), terphenyl compounds, alkyl compounds, alkylation Examples thereof include diphenyl ether (eg, propyl diphenyl ether), hydrogenated terphenyl (eg, hexahydroterphenyl), diphenyl ether and the like.

Of these, the use of esters is particularly preferable from the viewpoint of the emulsion stability of the emulsion dispersion. Examples of the esters include phosphates, phthalates, dioctyl tetrahydrophthalate, benzoates, abiates, dioctyl adipates, isodecyl succinate, dioctyl azelate, oxalates, diethyl malonate, maleates, Examples thereof include tributyl citrate, sorbate ester, sebacate ester, ethylene glycol esters, triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate and borate ester.

Specific examples of these esters are, for example,
It is described in JP-A-4-371887. In particular, the use of tricresyl phosphate alone or in combination is preferable because the emulsion dispersion stability of the color developer is particularly good. It is also possible to use the above oils in combination, or to use in combination with other oils. In the present invention, an auxiliary solvent may be added to the above organic solvent as a low boiling point dissolution aid. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase containing these components is appropriately selected from known anionic polymers, nonionic polymers and amphoteric polymers. However, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable. The surfactant contained in the aqueous phase may be appropriately selected from anionic or nonionic surfactants that do not cause precipitation or aggregation by acting on the protective colloid. As a preferred surfactant,
Examples thereof include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sodium sulfosuccinate, and polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether).

The emulsified dispersion in the present invention comprises an oil phase containing the above-mentioned components, a protective colloid, and an aqueous phase optionally containing a surfactant.
It can be easily obtained by mixing and dispersing using a means usually used for emulsification of fine particles. The ratio of the oil phase to the water phase (oil phase weight / water phase weight) is 0.0
2 to 0.6 is preferable, and 0.1 to 0.4 is particularly preferable.
Is preferred. If it is less than 0.02, the amount of the aqueous phase is too large to be diluted, and sufficient color developability cannot be obtained.
When it exceeds 6, the viscosity of the liquid becomes high, resulting in inconvenience in handling and deterioration in coating liquid stability.

In the present invention, a heat-fusible substance may be contained in the heat-sensitive color forming layer in order to improve the heat response of the heat-sensitive recording material. Examples of preferable heat-fusible substances include benzyl p-benzyloxybenzoate, β-naphthyl-benzyl ether, stearamide, stearyl urea, p-benzylbiphenyl, di (2-methylphenoxy) ethane, di (2 -Methoxyphenoxy) ethane, β-naphthol- (p-methylbenzyl) ether, α-naphthylbenzyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-tert-octylphenyl ether,
1-phenoxy-2- (4-ethylphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1,4-butanediol phenyl ether, diethylene glycol-bis (4-methoxyphenyl) ether and the like can be mentioned. To be

The heat fusible substances may be used alone or as a mixture. In order to obtain a sufficient thermal response, it is preferable to use the heat-fusible substance in an amount of 10 to 200% by weight, particularly preferably 20 to 150% by weight, based on the developer. In the present invention, the color former, the developer and the heat-fusible substance are dispersed in a water-soluble binder. The binder used in the present invention is preferably a polymer compound capable of dissolving 5% by weight or more in water at 25 ° C., specifically, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, starches (modified starch Include), gelatin, gum arabic, casein, hydrolyzate of styrene-maleic anhydride copolymer, carboxy-modified polyvinyl alcohol, polyacrylamide, saponified product of vinyl acetate polyacrylic acid copolymer, and the like.

These binders are not only used at the time of dispersion,
It can also be used for the purpose of improving the coating strength and further improving the coating suitability to obtain a uniform coated surface state.
In particular, carboxymethyl cellulose is used as the compound of the present invention
A uniform coated surface can be formed by using in combination with the compound represented by. Further, in the heat-sensitive recording layer, if necessary, a pigment, a metallic soap, a wax, an antistatic agent, an ultraviolet absorber, a surfactant, a defoaming agent, a conductive agent,
You may add fluorescent paint etc.

As the pigment, calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica, amorphous silica, aluminum hydroxide and the like are used. As the metal soap, higher fatty acid metal salts such as zinc stearate, calcium stearate and aluminum stearate are used.

As the wax, paraffin wax,
Microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax, fatty acid amide wax, etc. may be used alone or in combination. As a surfactant,
A sulfosuccinic acid-based alkali metal salt and a fluorine-containing surfactant are used.

These materials are mixed and then applied to the support. The coating amount of the heat-sensitive coloring layer is not particularly limited, usually, 1 to 10 g / m ² in dry weight, preferably from 2 to 8 g / m ^2. The most important feature of the heat-sensitive recording material of the present invention is that the heat-sensitive recording layer contains the compound represented by Chemical formula 2 above. Furthermore, in the thermal recording layer
The compound may be contained in an adjacent layer. The addition amount of the compound represented by the chemical formula 2 added to the coating liquid is
The solid content is in the range of 0.001 to 1.0% by weight, and particularly 0.005 to 0.1% by weight, although it varies depending on the coating method, coating speed, viscosity before adding the compound, and the like. It is preferable. If the amount of the compound added is less than 0.001% by weight, the thickening effect is insufficient and a uniform surface state cannot be obtained. If the addition amount exceeds 1% by weight, the thickening effect becomes excessive, and the coating liquid exhibits remarkable spinnability, which deteriorates the operability and makes the stretching in the coating unstable, resulting in a uniform surface condition. I can't.

The heat-sensitive recording layer of the heat-sensitive recording material of the present invention can be coated by a conventionally known coating method, for example, air knife coating, blade coating, gravure coating,
It is applied by bar coating, spray coating, dip coating, curtain coating or the like. Among them, the combination of a curtain coating method in which a free-falling curtain film is formed and applied to a running support to be applied and a coating solution containing the compound represented by the chemical formula 2 gives the highest image quality. In addition to being able to record an image and obtaining a heat-sensitive recording material with a uniform surface,
It is preferable because it has high productivity. The applied heat-sensitive recording material is dried, treated with a calendar or the like, and then used.

The support used in the present invention may be transparent or opaque. Examples of opaque supports include paper, coated paper, synthetic paper, paper laminated with polymer film, aluminum vapor deposition base, polymer film coated with white pigment, etc., but improved thermal sensitivity Therefore, it is preferable to provide an undercoat layer containing a pigment and a binder as main components.

Examples of the transparent support include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate film, polystyrene films, polypropylene films, polyolefin films such as polyethylene films, polyimide films and polychlorinated films. Vinyl film, polyvinylidene chloride film, polyacrylic acid copolymer film, polycarbonate film and the like can be mentioned, and these can be used alone or by laminating, but especially polyester film which has been subjected to heat treatment and antistatic treatment. Is preferred. A support having a thickness of 20 to 200 μm is used, and particularly 50 to 1
It is preferably 00 μm.

[0043]

The heat-sensitive recording material of the present invention is a heat-sensitive recording material having a uniform surface shape and capable of recording high-quality images, and is more excellent than conventional heat-sensitive recording materials. By adopting, it is possible to efficiently manufacture.

[0044]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, the parts and percentages described below
Indicates parts by weight and% by weight, respectively.

Example 1. (Preparation of coating liquid for heat-sensitive recording layer) Preparation of liquid A 10 parts of 3-dibutylamino-6-methyl-7-anilinofluorane and 5% polyvinyl alcohol solution (PV
A-105: trade name of Kuraray Co., Ltd.) A liquid having a composition of 50 parts was used, and the average particle size was 1.0 μm in a sand mill.
A dispersion of m was obtained.

Preparation of Solution B 20 parts of bisphenol A, naphthyl benzyl ether 2
A liquid having a composition of 0 part and 200 parts of polyvinyl alcohol was used to obtain a dispersion liquid having an average particle diameter of 1.0 μm by a sand mill.

Preparation of Liquid C A liquid having a composition of 40 parts of light calcium carbonate, 1 part of sodium polyacrylate and 60 parts of water was used to obtain a pigment dispersion liquid having an average particle diameter of 2.0 μm by a sand mill. Liquid A above 6
0 parts, B solution 240 parts, C solution 101 parts and zinc stearate 21% dispersion liquid 25 parts were mixed to obtain a thermal recording layer coating solution. 0.4% by weight of a surfactant was added to the obtained coating liquid for the heat-sensitive recording layer, and further Sterochol AL (acrylic acid / acrylamide copolymer Na of BASF) was added.
0.005% of salt and W / O emulsion) was added, and curtain coating was performed at a speed of 600 m / min to obtain a heat-sensitive recording material.

Example 2. A thermosensitive recording material was obtained in the same manner as in Example 1 except that 0.2% of serogen EP (trade name of sodium carboxymethyl cellulose manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added.

Example 3. No surfactant added, speed 20
Example 1 except that air knife coating was performed at 0 m / min.
A heat-sensitive recording material was obtained in the same manner as in.

Comparative Example 1. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that Sterochol AL was not added.

Comparative Example 2. Without adding Sterochol AL,
Further, a heat-sensitive recording material was obtained in the same manner as in Example 1 except that 0.7% of the serogen EP was added.

Comparative Example 3. A heat-sensitive recording material was obtained in the same manner as in Example 3 except that Sterochol AL was not added.

The results of evaluation of the thermal recording materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1 below.

[Table 1] In addition, (Note) in Table 1 indicates that there was an uncoated portion and measurement was impossible. Further, the sensitivity, image quality and coated surface condition in the table were measured as follows.

Method of measuring sensitivity Thermal head manufactured by Kyocera Corporation (KLT-216-
8MPD1) and a thermal printer having a pressure of 100 Kg / cm ² immediately before the head, a head voltage of 18.5.
Under a condition of V and a pulse cycle of 10 milliseconds, printing was performed with a pulse width of 1.2 milliseconds while using a pressure roll, and the density of the printed portion was measured with a Macbeth reflection densitometer RD-918.

Evaluation Method of Image Quality The above printed samples were visually evaluated. The judgment criteria are as follows. ⊚--Excellent. ○ --- It is excellent. Δ −−−−− Inferior. × −−−−− Very poor.

Coating Surface State The above printed samples were visually evaluated. The criteria for judgment are as follows. Good --- Good .DELTA .---- There is coating unevenness. × −−−−− There are uncoated portions.

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Claims (2)

(57) [Claims] To 1. A on a support, a thermosensitive recording material formed by providing a heat-sensitive recording layer containing a color developer that develops color in contact with at least a color former and emitting colorant, a heat-sensitive recording layer, the following A heat-sensitive recording material containing 0.001 to 1% by weight of the compound represented by Chemical formula 1. [Chemical 1] In the formula, m represents an integer of 3 to 20, n represents an integer of 7 to 47, and the ratio of m and n is between 1: 9 and 5: 5. 2. A method for producing the heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer is applied by a free-fall curtain coating method.